Techniques for thermal management within optical subassembly modules and a heater device for laser diode temperature control

ABSTRACT

The present disclosure is generally directed to techniques for thermal management within optical subassembly modules that include thermally coupling heat-generating components, such as laser assemblies, to a temperature control device, such as a thermoelectric cooler, without the necessity of disposing the heat-generating components within a hermetically-sealed housing. Accordingly, this arrangement provides a thermal communication path that extends from the heat-generating components, through the temperature control device, and ultimately to a heatsink component, such as a sidewall of a transceiver housing, without the thermal communication path extending through a hermetically-sealed housing/cavity.

RELATED APPLICATIONS

The present disclosure is related to co-pending application Ser. No.16/987,096 (Atty. Docket. No. PAT285US) titled “TECHNIQUES FOR THERMALMANAGEMENT WITHIN OPTICAL SUBASSEMBLY MODULES” which was concurrentlyfiled with the instant application and is incorporated herein byreference in its entirety.

TECHNICAL FIELD

The present disclosure relates generally to optical communications, andmore particularly, to techniques for providing thermal management withinoptical subassembly modules to minimize or otherwise reduce conditionsgiving rise to condensation without the necessity of hermetically-sealedhousings to protect components, and a heater device for laser diode (LD)temperature control.

BACKGROUND INFORMATION

Optical transceivers are used to transmit and receive optical signalsfor various applications including, without limitation, internet datacenter, cable TV broadband, and fiber to the home (FTTH) applications.Optical transceivers provide higher speeds and bandwidth over longerdistances, for example, as compared to transmission over copper cables.The desire to provide higher transmit/receive speeds in increasinglyspace-constrained optical transceiver modules has presented challenges,for example, with respect to thermal management, insertion loss, RFdriving signal quality and manufacturing yield.

Optical transceiver modules generally include one or more transmitteroptical subassemblies (TOSAs) for transmitting optical signals. TOSAscan include one or more lasers to emit one or more channel wavelengthsand associated circuitry for driving the lasers. In optical applicationssuch as long-distance communication and scenarios where condensation canform within optical transceiver module housings, for example,hermetically-sealed housings can be implemented to mitigate thepotential for performance loss and component degradation. However, theinclusion of hermetically-sealed components increases manufacturingcomplexity, cost, and raises numerous non-trivial challenges withinspace-constrained housings.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages will be better understood byreading the following detailed description, taken together with thedrawings wherein:

FIG. 1 is a block diagram of an optical transceiver module, consistentwith embodiments of the present disclosure.

FIG. 2 is a perspective view of an optical transceiver module consistentwith the present disclosure.

FIG. 3 shows the optical transceiver module of FIG. 2 partiallyexploded, in accordance with an embodiment of the present disclosure.

FIG. 4 shows another perspective view of the optical transceiver moduleof FIG. 2 with a first (or bottom) housing portion omitted, inaccordance with an embodiment of the present disclosure.

FIG. 5 shows another perspective view of the optical transceiver moduleof FIG. 2 with a second (or top) housing portion omitted, in accordancewith an embodiment of the present disclosure.

FIG. 6 shows a cross-sectional view of the optical transceiver module ofFIG. 2 taken along line 6-7.

FIG. 7 shows another cross-sectional view of the optical transceivermodule of FIG. 2 taken along line 6-7.

FIG. 8A shows a substrate and a plurality of laser assemblies suitablefor use in the optical transceiver module of FIG. 2 in isolation, inaccordance with an embodiment of the present disclosure.

FIG. 8B shows an enlarged portion of the substrate and the plurality oflaser assemblies shown in FIG. 8A, in accordance with an embodiment ofthe present disclosure.

FIG. 9A shows a perspective view of an example laser diode (LD) submountsuitable for use in the optical transceiver module of FIG. 2, inaccordance with an embodiment of the present disclosure.

FIG. 9B shows a top view of the LD submount of FIG. 9A, in accordancewith an embodiment of the present disclosure.

FIG. 10A shows a perspective view of an example heater device suitablefor use with the LD submount of FIG. 9A, in accordance with anembodiment of the present disclosure.

FIG. 10B shows a top view of the heater device of FIG. 10A, inaccordance with an embodiment of the present disclosure.

FIGS. 11A-11C show an example process for forming the heater device ofFIG. 10A in accordance with an embodiment.

FIG. 12 shows another perspective view of an LD submount suitable foruse in the optical transceiver module of FIG. 2, in accordance with anembodiment of the present disclosure.

DETAILED DESCRIPTION

As discussed above, existing optical subassembly modules such as TOSAsinclude hermetically-sealed housings and components to, among otherthings, reduce the potential for moisture/condensation to form andpotentially degrade optical performance and/or component lifespan. Inaddition, hermetically-sealed housings and components may also beutilized in combination with temperature control devices to maintainnominal optical performance. For example, in the context of TOSAs thatutilize electro-absorption modulated lasers (EMLs), hermetically-sealedhousings and temperature control devices such as thermoelectric coolers(TECs) often get implemented to regulate temperature and maintainnominal optical performance. However, such hermetically-sealed housingsincrease both manufacturing complexity and costs. Continued advancementsin scaling of optical transceiver modules to increase component density,reducing manufacturing costs and complexity, and increasing powerefficiency depends at least in part on thermal management approachesthat reduce or otherwise eliminate the necessity of hermetically-sealedhousings.

Thus, the present disclosure is generally directed to techniques forthermal management within optical subassembly modules that includethermally coupling heat-generating components, such as laser assemblies,to a temperature control device, such as a thermoelectric cooler,without the necessity of disposing the heat-generating components withina hermetically-sealed housing. Accordingly, this arrangement provides athermal communication path that extends from the heat-generatingcomponents, through the temperature control device, and ultimately to aheatsink component (e.g., a sidewall of a transceiver housing), withoutthe thermal communication path extending through a hermetically-sealedhousing/cavity.

The present disclosure has identified that conditions giving rise tocondensation in an optical subassembly module tend to occur whentransitioning from a relatively warm temperature internal temperature,e.g., 60-70 degrees Celsius (C) to temperatures below a dew point.

Thus, aspects of the present disclosure include utilizing an externaltemperature control system, e.g., an HVAC system, to maintain an ambienttemperature of an environment surrounding one or more opticalsubassembly modules implementing thermal management techniquesconsistent with the present disclosure. The one or more opticalsubassembly modules may then be held by such external temperaturecontrol systems at a target temperature, also referred to herein as aglobal temperature. In an embodiment, the HVAC system maintains theglobal temperature for the surrounding environment at 55±20° C.,preferably 55±10° C., and more preferably at 55±2° C. An opticaltransceiver module consistent with the present disclosure may thenmaintain a target local temperature (which may also be referred toherein as a local operating temperature or simply an operatingtemperature) that is 10-25° C. greater than the global temperature, andpreferably, at least 20° C. greater than the global temperature via anassociated temperature control device disposed within the opticaltransceiver module. Accordingly, the optical transceiver module maymaintain temperatures within a cavity defined by the same between 65-80°C., and preferably at 75±5° C. Thus, the optical transceiver module maythen minimize or otherwise reduce conditions giving rise to condensationby maintaining the local temperature above, or equal, to that of theglobal temperature.

Aspects of the present disclosure also include preferably thermallyisolating a substrate, such as a printed circuit board assembly (PCBA),from a temperature control device within an optical subassembly housing.Thus, the substrate can be utilized to couple to and support variousoptical subassembly components such as ROSA and TOSA components that arerelatively temperature-sensitive, without communicating heat to thesubstrate that could interfere with such temperature-sensitivecomponents.

In one preferred example, a region of a PCBA gets sandwiched between aplurality of laser assemblies and a thermoelectric cooler (TEC). In thisexample, the plurality of laser assemblies (directly) thermally coupleto the TEC by extending through one or a plurality of openings definedby the PCBA. Further, at least one layer of a thermally insulatingmaterial is disposed on the PCBA to thermally isolate the PCBA from theTEC. Accordingly, one or a plurality of thermal communication paths canextend between the plurality of laser assemblies and the TEC withoutpassing through the PCBA. Preferably, the one or plurality of thermalcommunication paths extend along an axis that is substantiallytransverse relative to the longitudinal axis of the substrate, and morepreferably, extend along an axis on which the TEC and plurality of laserassemblies are disposed to provide a relatively straight/direct thermalcommunication path.

In addition, the layer of thermally insulating material may also act asa heat conduit to channel heat towards the thermal communication path toincrease thermal communication and reduce the amount of heatcommunicated into the PCBA. Alternatively, or in addition, a gap isdisposed between the PCBA and the TEC. The gap may be provided by, forexample, one or a plurality of pedestals provided by the plurality oflaser assemblies to provide a mounting surface for the TEC that isoffset from the PCBA.

Aspects of the present disclosure also include a laser submount (alsoreferred to herein as an LD submount) for use within transmitter opticalsubassemblies (TOSAs) such as the optical transceiver module 100discussed below. The laser submount comprises a substrate, a laser diode(LD) coupled to the substrate, a first electrically conductive pathdisposed on the substrate to electrically couple the LD to LD drivingcircuitry, and a heater device disposed on the substrate. The heaterdevice preferably includes a base with a resistive heating element andan electrical conductor disposed thereon. More preferably, theelectrical conductor is disposed on the resistive heating element with alayer of electrically insulating material disposed therebetween to allowfor the electrical conductor to thermally couple to, and be electricallyisolated from, the resistive heating element. The electrical conductorcan provide at least a portion of the first electrically conductive pathto electrically couple the LD with the LD driving circuitry. The heaterdevice can be configured to communicate heat generated by the resistiveheating element to the LD, and preferably, the lasing region ormodulator region of the LD, based on an electrical interconnect thatelectrically couples the LD to the electrical conductor. Preferably, theelectrical interconnect comprises a wire bond or any other suitableelectrical interconnect that can communicate both an electricaldriving/radio frequency (RF) signal and heat generated by the resistiveheating element.

Thus, the laser submount advantageously provides a heater device thatprovides a portion of the first electrically conductive path to couplethe LD to LD driving circuitry. The heater device then communicatesgenerated heat to the LD, and preferably a lasing and/or a modulatorregion of the LD, via the first electrically conductive path.Integrating the heater device into the electrically conductive pathadvantageously reduces the footprint of the heater device on the LDsubmount and allows for greater component density and continued scalingof optical subassemblies.

As used herein, “channel wavelengths” refer to the wavelengthsassociated with optical channels and may include a specified wavelengthband around a center wavelength. In one example, the channel wavelengthsmay be defined by an International Telecommunication (ITU) standard suchas the ITU-T dense wavelength division multiplexing (DWDM) grid. Thisdisclosure is equally applicable to coarse wavelength divisionmultiplexing (CWDM). In one specific example embodiment, the channelwavelengths are implemented in accordance with local area network (LAN)wavelength division multiplexing (WDM), which may also be referred to asLWDM.

The term “coupled” as used herein refers to any connection, coupling,link or the like and “optically coupled” refers to coupling such thatlight from one element is imparted to another element. Likewise, theterm “thermally coupled” as used herein refers to any connection,coupling, link or the like between elements such that heat from oneelement is imparted to another element. Such “coupled” devices are notnecessarily directly connected to one another and may be separated byintermediate components or, in the context of optical coupling, devicesthat may manipulate or modify such signals. On the other hand, the term“direct optical coupling” refers to an optical coupling via an opticalpath between two elements that does not include such intermediatecomponents or devices, e.g., a mirror, waveguide, and so on, orbends/turns along the optical path between two elements. Likewise, theterm “direct thermal coupling” or “directly thermally coupled” refers toa coupling that communicates heat between two elements that does notinclude an intermediate component or device (including air and othergasses).

The term substantially, as generally referred to herein, refers to adegree of precision within acceptable tolerance that accounts for andreflects minor real-world variation due to material composition,material defects, and/or limitations/peculiarities in manufacturingprocesses. Such variation may therefore be said to achieve largely, butnot necessarily wholly, the stated/target characteristic. To provide onenon-limiting numerical example to quantify “substantially,” such amodifier is intended to include minor variation that can cause adeviation of up to and including ±5% from a particular statedquality/characteristic unless otherwise provided by the presentdisclosure.

As used herein, the terms hermetic-sealed and hermetically-sealed may beused interchangeably and refer to a housing that, for example, releasesa maximum of about 5*10⁻⁸casec of filler gas. The filler gas maycomprise an inert gas such as nitrogen, helium, argon, krypton, xenon,or various mixtures thereof, including a nitrogen-helium mix, aneon-helium mix, a krypton-helium mix, or a xenon-helium mix.

The use of the terms “first,” “second,” and “third” when referring toelements herein are for purposes of clarity and distinguishing betweenelements, and not for purposes of limitation. Likewise, like numeralsare utilized to reference like elements/components between figures.

Referring to the Figures, FIG. 1 shows a block diagram of an opticaltransceiver module 100 consistent with embodiments of the presentdisclosure. As shown, the optical transceiver module 100 includes aplurality of components disposed within housing 101, which may also bereferred to as an optical transceiver housing or an optical subassemblyhousing. Preferably, the housing 101 is implemented as a small-formfactor pluggable (SFFP) transceiver housing.

As shown, the housing 101 of the optical transceiver module 100 includesa transmitter optical subassembly (TOSA) arrangement 104 and a receiveroptical subassembly (ROSA) arrangement 106 coupled to a substrate 102,which may also be referred to herein as an optical module substrate.

The substrate 102 may comprise, for example, a printed circuit board(PCB), and preferably a PCB assembly (PCBA). Preferably, an end of thesubstrate 102 is configured to extend from the housing 101 to allow for“pluggable” insertion of the optical transceiver module 100 into atransceiver cage (not shown) and electrical interconnection withexternal driving circuitry, for example.

Preferably, the TOSA and ROSA arrangements 104, 106 are implemented asmulti-channel subassemblies configured to send and receive,respectively, N channel wavelengths and achieve overall transmissionspeeds of at least 40 Gigabits per second (Gb/s). More preferably, theTOSA and ROSA arrangements 104, 106 are configured to send and receive,respectively, four (4) different channel wavelengths and achieve overalltransmission speeds of at least 400 Gb/s. Other channel configurationsand transmission speeds are within the scope of this disclosure. TheTOSA arrangement 104 may therefore also be referred to herein as amulti-channel TOSA arrangement and the ROSA arrangement 106 may also bereferred to as a multi-channel ROSA arrangement.

As shown in FIG. 1, the optical transceiver module 100 transmits andreceives four (4) channels using four different channel wavelengths (λ1. . . λ4) via the TOSA arrangement 104 and the ROSA arrangement 106,respectively, and is capable of transmission rates of at least about 25Gbps per channel, and preferably, 50 Gbps per channel. The opticaltransceiver module 100 may also be capable of transmission distances of2 km to at least about 10 km. The optical transceiver module 100 may beused, for example, in internet data center applications or fiber to thehome (FTTH) applications. Although the following examples andembodiments show and describe a 4-channel optical transceiver module,this disclosure is not limited in this regard.

As further shown, the optical transceiver module 100 includes a transmitconnecting circuit 112 to provide electrical connections to theplurality of laser assemblies 110 and drive the same. The transmitconnecting circuit 112 may be configured to receive driving signals(e.g., TX_D1 to TX_D4) from, for example, external driving circuitryprovided by a transceiver cage (not shown). A plurality of transit (TX)traces 117 (also referred to herein as electrically conductive paths)may be patterned on a component mounting surface of the substrate 102 tobring the transmit connecting circuit 112 into electrical communicationwith the plurality of laser assemblies 110. The substrate 102 caninclude other components and conductive traces depending on a desiredconfiguration. For example, and as discussed in greater detail below,the substrate 102 can include terminals to electrically couple thetemperature control device 168 with a power rail. Notably, thetemperature control device 168 and/or the plurality of laser assemblies110 do not necessarily require a feedthrough device for electricalinterconnection with power and driving circuitry, thus reducingmanufacturing complexity and simplifying routing of electricalinterconnects relative to other approaches that implement TOSAs withinhermetically-sealed housings.

In the example of FIG. 1, the TOSA arrangement 104 includes a pluralityof laser assemblies 110 and a multiplexing device 125. Each of theplurality of laser assemblies 110 include at least one laser diode (LD)implemented as, for example, a direct modulated laser or an EML, andpreferably, at least one EML laser. Each laser assembly of the pluralityof laser assemblies 110 can further include passive and/or activeoptical components such as an optical isolator, focus lens, monitorphotodiode (MPD), as is discussed in greater detail below.

The multiplexing device 125 comprises an arrayed waveguide grating (AWG)or any other suitable device for combining a plurality of channelwavelengths and outputting a multiplexed optical signal via externaltransmit waveguide 120. The multiplexing device 125 may thereforeinclude a plurality of input ports optically coupled to the plurality oflaser assemblies 110 and be configured to receive channel wavelengths126 emitted by the same, and an output port optically coupled to opticalcoupling receptacle 122-1 by way of an intermediate waveguide, such asan optical fiber. The optical coupling port 122-1 may comprise, forexample, an LC port, or any other port for optically coupling to one ormore external transmit waveguides, e.g., external transmit waveguide120.

As further shown, the TOSA arrangement 104 includes a temperaturecontrol device 168 thermally coupled to the plurality of laserassemblies 110. The temperature control device 168 preferably directlythermally couples with the plurality of laser assemblies 110 as isdiscussed in further detail below. The temperature control device 168can be implemented as a thermoelectric cooler (TEC) device having aplurality of semiconductor elements (or Pelletier elements) sandwichedbetween two or more plates. In this example, the temperature controldevice 168 may be configured to selectively increase and decrease thetemperature of the plurality of laser assemblies 110 to maintain atarget local temperature. More preferably, the temperature controldevice 168 is implemented within the housing 101 without being disposedin, or otherwise coupled to, a hermetically-sealed housing/cavity. Thetemperature control device 168 can define a first thermal communicationpath generally shown at 113 that extends from the plurality of laserassemblies 110 to the housing 101 for heat dissipation purposes.

In operation, the TOSA arrangement 104 may then receive driving signals(e.g., TX_D1 to TX_D4), and in response thereto, generate and launchmultiplexed channel wavelengths on to the external transmit waveguide120, preferably implemented as an optical fiber, by way of opticalcoupling receptacle 122-1.

The present disclosure has identified that conditions giving rise tomoisture/condensation within the housing 101 may be mitigated via athermal management approach that does not require implementing the TOSAarrangement 104, whole or in part, within a hermetically-sealed cavity.Therefore, the TOSA arrangement 104 is preferably not disposed within ahermetically-sealed cavity/housing, and instead, is disposed in anatmosphere within the cavity of the housing 101 shared by each componenttherein. The atmosphere of the cavity in which the TOSA arrangement 104is disposed may therefore comprise substantially oxygen, and have acomposition and atmospheric pressure substantially identical to theexternal atmosphere surrounding the optical transceiver module 100.Stated differently, the TOSA arrangement 104 is preferably not disposedwithin a pressurized housing.

For in-door or otherwise temperature controlled environments surroundingthe optical transceiver module 100, e.g., featuring an HCAV system, suchexternal atmospheres may be kept at substantially a nominal ambienttemperature (also referred to herein as a global temperature) of 50degrees Celsius or less. In this example, the temperature control device168 may therefore be configured to maintain a target local temperaturefor the plurality of laser assemblies 110 by, for instance, heating thesame until the target local temperature is reached. In the context ofthe plurality of laser assemblies 110 being implemented with EML lasers,for example, the target local temperature may be between 20 and 70degrees Celsius. Preferably, the temperature control device 168 isconfigured to increase the temperature of the plurality of laserassemblies 110 by at least 20 degrees Celsius relative to the globaltemperature of the environment surrounding the optical transceivermodule 100.

Condensation conditions tend to occur when relatively warm components ofthe optical transceiver module 100 begin to cool. Accordingly,conditions giving rise to condensation are minimized or otherwisereduced by the temperature control device 168 maintaining the pluralityof laser assemblies 110 above the global temperature, e.g., at thetarget local temperature, and maintaining the plurality of laserassemblies 110 within ±20 degrees Celsius of the target localtemperature, preferably within ±5 degrees Celsius, and more preferablywithin ±2 degrees Celsius of the target local temperature.

Continuing on, the ROSA arrangement 106 preferably includes ademultiplexing device 124, a photodiode (PD) array 128, andamplification circuitry 130. The demultiplexing device 124 is preferablyimplemented as an arrayed waveguide grating, and the amplificationcircuitry 130 is preferably configured as at least one transimpedanceamplifier (TIA). An input port of the demultiplexing device 124 may beoptically coupled with an external receive waveguide 134, e.g.,implemented as an optical fiber, by way of an optical couplingreceptacle 122-2. Optical coupling receptacle 122-2 is preferablyimplemented as an LC port, although other types of optical couplingports are within the scope of this disclosure. An intermediatewaveguide, such as an optical fiber, optically couples the opticalcoupling receptacle 122-2 with the demultiplexing device 124.

An output port of the demultiplexing device 124 is preferably configuredto output separated channel wavelengths on to the PD array 128. The PDarray 128 may then output proportional electrical signals to theamplification circuitry 130, which then may be amplified and otherwiseconditioned. The PD array 128 and the amplification circuitry 130 candetect and convert optical signals into electrical data signals (RX_D1to RX_D4) that are output via the receive connecting circuit 132. Inoperation, the PD array 128 may then output electrical signals carryinga representation of the received channel wavelengths to a receiveconnecting circuit 132 by way of conductive traces 119 (which may bereferred to as conductive paths).

Referring to FIGS. 2-8B an example optical transceiver module 200 isshown consistent with an embodiment of the present disclosure. Theoptical transceiver module 200 may be implemented as the opticaltransceiver module 100 of FIG. 1.

As shown in FIG. 2, the optical transceiver module 200 includes housing201. In one preferred example, the optical transceiver module 200includes the housing 201 implemented as a small form-factor pluggable(SFFP) housing. The optical transceiver module 200 is also preferablyconfigured to send and receive four (4) different channel wavelengthsand operates at speeds of at least 400 gigabits per second (Gb/s),although other configurations are within the scope of this disclosure.Note, aspects and features are equally applicable to other types ofoptical subassembly modules and not necessarily a multi-channel opticaltransceiver as shown and described variously herein. For example,aspects and features are equally applicable to transmitter-only, e.g.,stand-alone TOSAs, receiver-only devices, e.g., stand-alone ROSAs,and/or single-channel devices.

As shown, the housing 201 of the optical transceiver module 200comprises first and second housing portions 201-1 and 201-2 that coupletogether and define a cavity 255 (See FIG. 4) therebetween. The housing201 includes a first end 252-1 disposed opposite a second end 252-2along longitudinal axis 250.

Preferably, the first end 252-1 includes a portion of the substrate 202extending therefrom to electrically couple with the external transmitand receive circuitry, e.g., via transmit connecting circuit 112 andreceive connecting circuit 132 (See FIG. 1). The first end 252-1 mayalso be referred to as an electrical coupling end.

As shown, the second end 252-2 is configured to optically couple withexternal transmit waveguide 120 and external receive waveguide 134(FIG. 1) via optical coupling ports 222. Preferably, the opticalcoupling ports 222 are implemented as LC receptacles to couple to theexternal transmit and receive waveguides 120, 134. The second end 252-2may also be referred to herein as an optical coupling end.

The second end 252-2 further includes a handle 254 coupled to a lockingarrangement 258. Preferably, the locking arrangement 258 and handle 254allows for the housing 201 to be removably coupled into a transceivercage and securely held/locked in place by a detent 259 or other featureof the locking arrangement 258. A user may then grip the handle 254 andsupply a force along longitudinal axis 250 in a direction away from thetransceiver cage to cause the locking arrangement 258 todisengage/unlock by displacing the detent 259, for example, and allowfor the optical transceiver module 200 to be removed from thetransceiver cage.

FIG. 3 shows the optical transceiver module 200 of FIG. 2 partiallyexploded in accordance with an embodiment. As shown, the substrate 202is at least partially disposed in the cavity 255 (See FIG. 4) of thehousing 201. The substrate 202 preferably includes at least a firstcomponent mounting surface 280-1 (See FIG. 4) for supporting TOSA andROSA arrangements 204, 206 respectively, within the cavity 255. Morepreferably, the substrate 202 includes a second component mountingsurface 280-2 disposed opposite the first component mounting surface280-1 (See FIG. 7).

As further shown, the TOSA arrangement 204 includes a plurality of laserassemblies 210. Each laser assembly of the plurality of laser assemblies210 may also be referred to herein as mini TOSAs. Each laser assembly ofthe plurality of laser assemblies 210 optically couples to an input ofmultiplexing device 225 by way of intermediate waveguides 267 preferablyimplemented as optical fibers as shown. The multiplexing device 225further includes an output port optically coupled to the opticalcoupling ports 222 by way of an intermediate waveguide 269 preferablyimplemented as an optical fiber as shown. Preferably, the input andoutput ports of the multiplexing device 225 are located on the sameside. Likewise, the demultiplexing device 224 of the ROSA arrangement206 (See also FIG. 4) further includes an input port optically coupledto optical coupling ports 222 by way of an intermediate waveguide 263preferably implemented as an optical fiber.

Continuing on with FIG. 3, the optical transceiver module 200 includes asupport structure 264 disposed within the cavity 255 (See FIG. 4). Thesupport structure 264 preferably couples to and is supported by thesubstrate 202. The support structure 264 further defines anaccommodation groove 261. The accommodation groove 261 defines areceptacle to receive at least a portion of the multiplexing device 225therein. The accommodation groove 261 also further preferably defines aY-shaped channel to allow for routing of intermediate waveguides 267from the plurality of laser assemblies 210 to the input ports of themultiplexing device 225, and to allow for routing of the intermediatewaveguide 269 to the optical coupling ports 222.

Turning to FIGS. 4-5, FIG. 4 shows the optical transceiver module 200 ofFIG. 2 inverted and with the first housing portion 201-1 omitted, andFIG. 5 shows the optical transceiver module 200 of FIG. 2 with thesecond housing portion 201-2 omitted.

As shown, the substrate 202 includes the first component mountingsurface 280-1 disposed within the cavity 255 of the housing at alocation proximate the first housing portion 201-1 (See FIG. 5), andpreferably, the first component mounting surface 280-1 faces the firsthousing portion 201-1, e.g., when the first housing portion 201-1 iscoupled to the second housing portion 201-2.

The first component mounting surface 280-1 is configured to couple toone or more components. For example, the demultiplexing device 224 ofthe ROSA arrangement 206 couples to and is supported by a first regionof the first component mounting surface 280-1. In this example, the ROSAarrangement 206 may also be referred to as an on-board ROSA arrangement.

Further, a temperature control device 268 couples to and is supported bya second region of the first component mounting surface 280-1. Asdiscussed in greater detail below, the second region of the firstcomponent mounting surface 280-1 of the substrate 202 defines at least aportion of a laser mounting region (also referred to as a TOSA mountingregion) as discussed in greater detail below.

The temperature control device 268 preferably comprises a thermoelectriccooler having a plurality of semiconductor elements sandwiched/disposedbetween first and second plates 270-1, 270-2. The temperature controldevice 268 is also preferably used as a common/shared temperaturecontrol device by each of the plurality of laser assemblies 210. Thus,the temperature control device 268 may heat and/or cool the plurality oflaser assemblies 210 collectively. However, the temperature controldevice 268 may be implemented as a plurality of temperature controldevices, with each of the plurality of temperature control devicesheating/cooling one or a plurality of associated laser assemblies.

Preferably, the temperature control device 268 is disposed adjacent anend of the substrate 202, and in particular, the end of the substrate202 defining the laser coupling region. More preferably, the temperaturecontrol device 268 is disposed at an offset from the substrate 202 basedon gap 286 discussed in further detail below. The temperature controldevice 268 can include a longitudinal axis that is substantiallytransverse relative to the longitudinal axis 250 (See FIG. 2) of thehousing 201. For example, and as shown in FIG. 4, this allows thetemperature control device 268 to extend across the width of thesubstrate 202 and allow for thermal coupling with each laser assembly ofthe plurality of laser assemblies 210.

The temperature control device 268 can electrically couple viaconductors 272 (See FIG. 6) to the substrate 202, and more specifically,electrical terminals disposed on the first component mounting surface280-1 of the substrate 202. Preferably, the temperature control device268 is disposed in the cavity 255, with the cavity 255 beingnon-hermetically sealed. Thus, the temperature control device 268 canelectrically couple to circuitry of the optical transceiver module 200such as a controller and/or power rail, without the use of a feedthroughdevice.

FIG. 6 shows an example cross-sectional view of the optical transceivermodule 200 taken along line 6-7 of FIG. 1. In the preferred example ofFIG. 6, the temperature control device 268 couples to the plurality oflaser assemblies 210 and/or the first component mounting surface 280-1by way of the first plate 270-1. More preferably, the temperaturecontrol device 268 (directly) thermally couples to the plurality oflaser assemblies 210 by way of the first plate 270-1. The temperaturecontrol device 268 may then provide a first thermal communication path213 that extends at least from the plurality of laser assemblies 210 tothe temperature control device 268, and preferably, from the pluralityof laser assemblies 210 to the first housing portion 201-1 for heatdissipation purposes.

The temperature control device 268 may also thermally couple to thesubstrate 202 via a second thermal communication path (not shown) thatextends substantially parallel with the first thermal communication path213 and that passes through a portion of the substrate 202 disposedbetween the temperature control device 268 and the plurality of laserassemblies 210. However, and as is discussed further below, thesubstrate 202 can include a layer of thermally insulating materialdisposed thereon and/or have a gap disposed between the substrate 202and the temperature control device 268 to thermally isolate thesubstrate 202 from the temperature control device 268. Thus, the secondthermal communication path can be configured to communicatesubstantially less heat than the first thermal communication path basedon the layer of thermally insulating material and/or gapinterrupting/obstructing the same.

As shown, the second plate 270-2 of the temperature control device 268thermally couples to the first housing portion 201-1. Preferably, thesecond plate 270-2 of the temperature control device 268 directlythermally couples to the first housing portion 201-1. In this preferredexample, the second plate 270-2 of the temperature control device 268may therefore (directly) thermally couple with the first housing portion210-1 to increase communication of heat.

Preferably, each laser assembly of the plurality of laser assemblies 210can be configured as a cuboid-type laser, such as shown. Each laserassembly of the plurality of laser assemblies 210 includes acorresponding base, e.g., shown in FIG. 8A as 211-1 to 211-4. For easeof description and clarity, a cross-sectional view of the base 211-1taken along line 6-7 of FIG. 1 is shown in FIG. 7. Note, each laserassembly of the plurality of laser assemblies 210 preferably includes asubstantially similar configuration, and the following aspects andfeatures discussed with reference to FIG. 7 are equally applicable toeach laser assembly of the plurality of laser assemblies 210.

The base 211-1 comprises a metal or other suitably rigid material, andpreferably, a material with a relatively high thermal conductivity of62W/m-K or greater. As shown, the base 211-1 defines at least a firstmounting surface 284 for coupling to and supporting the temperaturecontrol device 268. Preferably, the temperature control device 268directly couples/mounts to the first mounting surface 284. As discussedin further detail below, each base 211-1 to 211-4 can define a pedestalto mount the temperature control device 268 at an offset to provide thegap 286 between the first component mounting surface 280-1 of thesubstrate 202 and the temperature control device 268. The gap 286 canprovide thermal isolation between the substrate 202 and the temperaturecontrol device 268. This advantageously minimizes or otherwise reducescommunication of heat from the plurality of laser assemblies 210 and/orthe temperature control device 268 to the substrate 202, and byextension, reduces the potential for communicating heat totemperature-sensitive components mounted to the substrate 202.

Continuing on, the base 211-1 further provides a laser mounting surface215-1, with the laser mounting surface 215-1 being disposed opposite thefirst mounting surface 284. As shown, the laser mounting surface 215-1is configured to couple to and support at least a portion of laserarrangement 213-1 that includes laser diode 294. The laser diode 294 maybe mounted/coupled directly to the laser mounting surface 215-1, orindirectly by way of a submount 299 as shown. Preferably, the laserdiode 294 is implemented as an EML, and thus the laser arrangement 213-1may also be referred to herein as an EML arrangement. The submount 299is preferably implemented as the laser submount 299A or the lasersubmount 299B of FIGS. 9A and 12, respectively, although otherconfigurations are within the scope of this disclosure.

The laser arrangement 213-1 can further include a monitor photodiode(MPD) 292, focus lens 296, and optical isolator 298. Each component ofthe laser arrangement 213-1 may be optically aligned along a light path285. Light path 285 may therefore be formed by aligning the componentsof the laser arrangement 213-1 along the X and Y axis.

The plurality of laser assemblies 210 may therefore define a pluralityof light paths, e.g., including light path 285, which extendsubstantially parallel with each other and substantially parallel withthe longitudinal axis 250 of the housing 201 (See FIG. 2).

Turning to FIG. 8A, the substrate 202 and plurality of laser assemblies210 are shown in isolation and partially exploded. Note, the temperaturecontrol device 268 has been omitted merely for clarity. As shown, thesubstrate 202 preferably includes a plurality of openings 242-1 to242-4. Each of the plurality of openings 242-1 to 242-4 can include anotched/grooved profile, such as shown, or may include other shapes andconfigurations.

The plurality of openings 242-1 to 242-4 generally define at least aportion of a laser coupling region (also referred to herein as a lasercoupling section). The laser coupling region further preferably includesa recessed surface 243, with the recessed surface 243 providing astepped profile. The recessed surface 243 can further define analignment surface 245, with the alignment surface 245 extendingsubstantially transverse relative to the first and second componentmounting surfaces 280-1, 280-2.

Preferably, a first layer of thermally insulating material 236 (See FIG.8B) is disposed on the first component mounting surface 280-1, andpreferably, in the laser coupling region. The first layer of thermallyinsulating material 236 can comprise, for example, glass-reinforcedepoxy laminate material commonly referred to as FR4, and preferablyCopper (Cu). The first layer of thermally insulating material 236 mayalso be referred to as a layer of thermal shielding.

As shown in the preferred example of FIG. 8A, the first layer ofthermally insulating material 236 is disposed between the temperaturecontrol device 268 and the first component mounting surface 280-1 of thesubstrate 202 (See FIG. 6). More preferably, the gap 286 is disposedbetween the temperature control device 268 and the first layer ofthermally insulating material 236 to provide additional thermalisolation between the temperature control device 268 and the substrate202.

One or more additional layers of thermally insulating material may alsobe disposed in other areas of the laser coupling region. For example, asecond layer of thermally insulating material 237 may be disposed on therecessed surface 243 (See FIG. 6). In another example, a layer ofthermally insulating material may also be disposed on surfaces definingthe plurality of openings 242-1 to 242-4.

As shown in FIG. 8B, the base of each laser assembly of the plurality oflaser assemblies 210 is configured to extend at least partially througha corresponding opening of the plurality of openings 242-1 to 242-2 tothermally couple to the temperature control device 268. For example, thebase 211-1 includes a projection 247-1 that extends from the base 211-1.The projection 247-1 preferably includes a tapered profile as shown witha shape that generally corresponds with the opening 242-1. Theprojection 247-1 and opening 242-1 may therefore form a tongue andgroove arrangement. The alignment surface 245 may then act as amechanical end stop to engage surface 251 and prevent further movementalong the X axis. Surface 252 of the base 211-1 extends substantiallytransverse relative to the surface 251 and provides a mating surface toengage recessed surface 243 and prevent further movement along the Zaxis. Thus, the plurality of openings 242-1 to 242-2 of the lasercoupling section allows for mechanical alignment of the plurality oflaser assemblies 210 during mounting of the same.

Preferably, each of the plurality of laser assemblies 210 includes eachassociated base having a mounting surface that extends substantiallyparallel with the first component mounting surface 280-1 of thesubstrate 202, such as is more clearly shown in FIG. 8B. For example,the projection 247-1 of base 211-1 is configured with an overall heightthat causes a mounting surface 241-1 of the projection 247-1 to have anoffset of D1 relative to the first component mounting surface 280-1, andan offset of D2 relative to the first layer of thermally insulatingmaterial 236. Preferably, the offset D1 is between 10 microns and 40microns. Likewise, the offset D2 is preferably between 0 microns and 10microns.

Accordingly, each laser assembly of the plurality of laser assemblies210 preferably defines a mounting surface, such as mounting surfaces241-1, that extends substantially coplanar with each other such that theplurality of laser assemblies 210 collectively provide a mountingsurface for (directly) coupling to and supporting the temperaturecontrol device 268. More preferably, the mounting surface collectivelyprovided by the plurality of laser assemblies 210 allows for thermallycoupling to the temperature control device 268 while also providingthermal isolation between the temperature control device 268 and thesubstrate 202, e.g., based on offsets D1/D2 and/or gap 286. Theprojection of each of the plurality of laser assemblies 210, e.g.,projection 247-1, may also be referred to as a temperature controldevice mounting pedestal or simply a pedestal.

Referring to FIGS. 9A-9B, a laser submount 299A is shown in accordancewith an embodiment of the present disclosure. The laser submount 299Amay also be referred to as an LD submount. The example laser submount299A is suitable for use in optical subassembly modules, such as theoptical transceiver module 100/200 of FIGS. 1 and 2 discussed above.

As shown, the laser submount 299A includes a base 902. The base 902 maybe any suitable substrate, and preferably, is a ceramic substrate. Thebase 902 preferably includes a component mounting surface 913 that issubstantially planar/flat.

The laser submount 299A includes a plurality of components coupled tothe component mounting surface 913 provided by the base 902. Inparticular, the laser submount 299A preferably includes a heater device904, a filtering capacitor 912, and the laser diode 994 coupled to andsupported by the component mounting surface 913. The laser diode 994preferably comprises an EML, although other types of laser devices arewithin the scope of this disclosure.

As shown, the laser diode 994 includes a lasing region 916-1 and amodulator region 916-2 (See FIG. 9B). The lasing region 916-1electrically couples with external driving circuitry (also referred toherein as external LD driving circuitry, or simply LD driving circuitry)via a first electrically conductive path that extends between the lasingregion 916-1 and the terminal/pad 964. Preferably, and as discussed ingreater detail below, the heater device 904 provides at least a portionof the first electrically conductive path to allow for the heater device904 to communicate heat to the laser diode 994, and more specifically,the lasing region 916-1 of the laser diode 994.

In more detail, the first electrically conductive path preferablyincludes the terminal/pad 964 disposed on the component mounting surface913 of the base 902 to receive a direct current (DC) bias signal from apower supply. Preferably, the electrical terminal 964 electricallycouples to the filtering capacitor 912 by way of one or more electricalinterconnects 922. More preferably, the one or more electricalinterconnects 922 are implemented as wire bond(s).

The filtering capacitor 912 can be configured to, for instance, bypassnoise from a DC power supply that provides the DC bias signal. Thefiltering capacitor 912 electrically couples to the heater device 904,and more particularly, an electrical conductor 906 disposed on theheater device 904. As discussed in further detail below, the heaterdevice 904 includes a resistive heating element 910 thermally coupledto, and electrically isolated from, the electrical conductor 906.

The electrical conductor 906 provides a first electrical terminal 903-1at an end/region adjacent the filtering capacitor 912. The firstelectrical terminal 903-1 of the electrical conductor 906 electricallycouples to the filtering capacitor 912 by way of at least one electricalinterconnect 924. Preferably, the at least one electrical interconnect924 comprises one or more wire bonds, such as shown in FIG. 9B. Theelectrical conductor 906 further provides a second electrical terminal903-2 at an end/region adjacent the laser diode 994. The secondelectrical terminal 903-2 of the electrical conductor 906 electricallycouples to the lasing region 916-1 of the laser diode 994 by way of atleast one electrical interconnect 918. Preferably, the at least oneelectrical interconnect 918 comprises one or more wire bonds, and morepreferably, the at least one electrical interconnect 918 comprises aplurality of wire bonds to increase communication of heat generated bythe resistive heating element 910 to the lasing region 916-1 of thelaser diode 994.

Preferably, the second electrical terminal 903-2 of the electricalconductor 906 includes an overall surface area that is larger than thatof the first electrical terminal 903-1. For example, the overall surfacearea of the second electrical terminal 903-2 may be at least twice theoverall surface area of the first electrical terminal 903-1. Thus, thesecond electrical terminal 903-2 may be configured to support aplurality of electrical interconnects such as wire bonds as shown inFIGS. 9A and 9B.

The modulator region 916-2 of the laser diode 994 electrically coupleswith external driving circuitry via a second electrically conductivepath that extends between the modulator region 916-2 and the electricalterminal/pad 926. The electrical terminal 926 preferably comprises alayer of metal disposed on the component mounting surface 913. Inparticular, the second electrically conductive path includes theelectrical terminal 926 to receive an electrical signal from externaldriving circuitry for driving the modulator region 916-2 of the laserdiode 994. The electrical terminal 926 electrically couples to themodulator region 916-2 by way of an electrical interconnect 928.Preferably, the electrical interconnect 928 comprises one or more wirebonds, such as show in FIG. 9B.

The second electrically conductive path further includes a matchingresistor 914 (also referred to herein as a matching resistor network)electrically coupled between a ground plane 920 and the modulator region916-2. The ground plane 920 preferably comprises at least one layer ofmetal disposed on the component mounting surface 913. More preferably,the ground plane 920 comprises a coplanar ground plane formed of anelectrically conductive material such as Copper (Cu). Preferably, thematching resistor 914 couples to the ground plane 920 and the modulatorregion 916-2 of the laser diode 994 via an electrical interconnect, suchas wire bonds as shown in FIG. 9B. The matching resistor 914 comprises,for example, one or more resistors and preferably one or more surfacemountable device (SMDs) such as a 50 Ohm resistor SMD device.

FIGS. 10A-10B show the heater device 904 of FIGS. 9A-9B in isolation, inaccordance with an embodiment of the present disclosure. As shown, theheater device 904 includes a base 905 with a cuboid shape. The base 905can include other shapes and profiles, depending on a desiredconfiguration. The base 905 preferably comprises a material with athermal conductivity of 1.5 Watts per meter-Kelvin (W/m-K) or less. Onesuch example material includes Quartz, although this disclosure is notlimited in this regard.

The base 905 preferably defines at least one mounting surface, such asmounting surface 911. The mounting surface 911 is preferably disposedopposite mating surface 917 by which the heater device 904 couples tothe base 902 of the laser submount 299A (See FIG. 9A). As further shown,the base 905 can include at least one groove 909. The at least onegroove 909 can be configured to provide projections/feet 919 formounting to the laser submount 299A, and for providing increased thermalisolation between the resistive heating element 910 and the lasersubmount 299A.

As further shown, the base 905 of the heater device 904 includes aplurality of components disposed on the mounting surface 911. As shown,this includes a resistive heating element 910 disposed on the mountingsurface 911. The resistive heating element 910 preferably includes alayer of a metal 929 disposed on the mounting surface 911, which can bemore clearly seen in FIG. 11A. The resistive heating element 910 furtherincludes first and second electrical terminals 927-1, 927-2 formed of asecond metal. The first and second electrical terminals 927-1, 927-2 arepreferably disposed on opposite sides of the layer of metal 929.Preferably, the first and second electrical terminals 927-1, 927-2comprise a different metal than that of the layer of metal 929. Thefirst and second terminals 927-1, 927-2 of the resistive heating element910 can electrically couple to external driving circuitry via, forexample, electrical interconnects 978 and 979, and electrical terminal977 (See FIG. 9B). Preferably the electrical interconnects 978 and 979each comprise one or more wire bonds.

Preferably, the first and second electrical terminals 927-1, 927-2directly electrically couple to the layer of metal 929. One examplematerial for the layer of metal 929 includes Tantalum nitride (TaN)although the layer of metal 929 can comprise other metals such as NiCr(Nichrome) or a metal with an electrical resistivity of 1.5×10-6 Ω·m orgreater. Preferably, the first and second electrical terminals 927-1,927-2 comprise a metal with an electrical resistivity less than that ofthe layer of metal 929, and more preferably, a metal with an electricalresistivity of less than 16.4×10-8 Ω·m. One example material for thesecond metal of the first and second electrical terminals 927-1, 927-2includes Gold (Au). The resistive heating element 910 may therefore beconfigured to generate heat based on an electrical signal provided tothe layer of metal 929 (See FIG. 11A) by way of the first and secondelectrical terminals 927-1, 927-2.

The base 905 further preferably includes a layer of electricallyinsulating material 930 disposed on the mounting surface 911, and morepreferably, disposed at least partially on the resistive heating element910. The layer of electrically insulating material 930 can comprise, forexample, at least one of Silicon dioxide (SiO2), Aluminum Nitride (AlN),Aluminum Oxide (Al2O3), Silicon Carbide (SiC), Silicon Nitride (Si3N4),and/or Polyimide.

The base 905 further preferably includes the electrical conductor 906disposed on the mounting surface 911, and more preferably, disposed atleast partially on the layer of electrically insulating material 930. Inthis preferred example, the layer of electrically insulating material930 electrically isolates the electrical conductor 906 from the layer ofmetal 929 of the resistive heating element 910, and thermally couplesthe resistive heating element 910 to the electrical conductor 906.

Heater device 904 may then preferably communicate heat generated by theresistive heating element 910 to, for example, the lasing region 916-1of the laser diode 994 via a thermal communication path that extendsthrough the layer of electrically insulating material 930 and theelectrical conductor 906 to the lasing region 916-1 of the laser diode994 by way of the at least one electrical interconnect 918 (See FIG.9B). Accordingly, the at least one electrical interconnect 918 thatelectrically couple the electrical conductor 906 to the lasing region916-1 of the laser diode 994 can communicate both a driving signal andheat to maintain the lasing region 916-1 of the laser diode 994 at atarget temperature. One such target temperature includes at least 20degrees Celsius.

FIGS. 11A-11C illustrate an example process to form the heater device904, in accordance with an embodiment. As shown in FIG. 11A, theresistive heating element 910 gets disposed on the base 905, andpreferably, across the mounting surface 911 of the base 905 fromedge-to-edge. More preferably, the resistive heating element 910includes the layer of metal 929 disposed at a midpoint of the base 905,and the first and second electrical terminals 927-1, 927-2 disposed onopposite sides of the layer of metal 929. As shown in FIG. 11B, thelayer of electrically insulating material 930 gets disposed on to thebase 905, and preferably, on to at least the layer of metal 929 of theresistive heating element 910. More preferably, the layer ofelectrically insulating material 930 gets disposed on the layer of metal929 and the mounting surface 911. As shown in FIG. 11C, the electricalconductor 906 may then be disposed on the base 905, and preferably, onthe layer of electrically insulating material 930. More preferably, theelectrical conductor 906 extends across the mounting surface 911 of thebase 905, e.g., edge-to-edge, along an axis that is substantiallytransverse relative to the axis along which the resistive heatingelement 910 extends.

FIG. 12 shows another example laser submount 299B in accordance with anembodiment of the present disclosure. The laser submount 299B includes asubstantially similar configuration to that of the laser submount 299Aof FIGS. 9A-9B, the description of which will not be repeated forbrevity.

However, as shown in FIG. 12, the laser submount 299B provides a firstelectrically conductive path that couples the modulator region 916-2 toexternal driving circuitry based at least in part on the heater device904′ . Preferably, the first electrically conductive path includeselectrical terminal 926 that couples to the modulator region 916-2 byway of an electrical interconnect 928, which is preferably implementedas one or more wire bonds as shown. The first electrically conductivepath further includes at least one matching resistor 914 that define aportion of the electrical conductor 906′. The electrical conductor 906′can comprise a metal, such as Gold (Au) or Copper (Cu), and providesfirst and second electrical terminals 903-1′ and 903-2′. The firstelectrical terminal 903-1′ electrically couple to the ground plane 920via one or more electrical interconnects, and preferably, via at leastone electrical interconnect implemented as a wire bond. Likewise, thesecond electrical terminal 903-2′ electrically couples to the modulatorregion 916-2 via one or more electrical interconnects, and preferably,via at least one electrical interconnect implemented as a wire bond.

The laser submount 299B preferably includes a second electricallyconductive path disposed thereon. The second electrically conductivepath electrically couples the lasing region 916-1 of the LD 994 toexternal LD driving circuitry. For example, as shown in FIG. 12, thesecond electrically conductive path extends from the electrical terminal964 to the filtering capacitor 912 by way of electrical interconnects922, and from the filtering capacitor 912 to the lasing region 916-1 ofthe LD 994 by way of electrical interconnects 961. The electricalinterconnects 922, 961 are preferably implemented as wire bonds.

The heater device 904′ can include a substantially similar configurationto that of the heater device 904 of FIGS. 9A-9B, the description ofwhich is equally applicable to the heater device 904′ and will not berepeated for brevity. However, and as shown, the heater device 904includes the electrical conductor 906′ being implemented in part by theat least one matching resistor 914. Preferably, the at least onematching resistor 914 comprises SMD-type resistors, and more preferably,a 50 ohm SMD.

In addition, and as shown, the second electrical terminal 903-2′preferably includes an overall surface area that is substantially equalto the overall surface area of the first electrical terminal 903-1′.Preferably, the second electrical terminal 903-2′ includes an overallsurface area sufficient to support and couple to a single electricalinterconnect 989, such as shown, although this disclosure is not limitedin this regard. The electrical interconnect 989 preferably comprises awire bond and can be used to communicate heat generated from theresistive heating element 910 of the heater device 904′ to the modulatorregion 916-2 via a thermal communication path that extends through thefirst layer of electrically insulating material 930, the electricalconductor 906′ (and more preferably the at least one matching resistor914), and the electrical interconnect 989. The electrical interconnect989 may therefore both provide an impedance matching scheme for themodulator region 916-2 of the laser diode 994 as well as heat tomaintain a target temperature of the modulator region 916-2 of the laserdiode 994. One such target temperature includes at least 20 degreesCelsius.

The heater device 904′ may be formed via a process substantially similarto the process discussed above with regard to FIGS. 11A-C. However, theprocess can include disposing the at least one matching resistor 914 onthe base 905 when forming the electrical conductor 906/906′. Preferably,the at least one matching resistor 914 is disposed at a midpoint/centerof the base 905, and more preferably, directly electrically coupled tothe first and second first and second electrical terminals 903-1′,902-2′ and on the first layer of the electrically insulating material930.

In accordance with another aspect of the present disclosure an opticalsubassembly module is disclosed. The optical subassembly modulecomprising a housing defining a cavity, a substrate at least partiallydisposed in the cavity, a thermoelectric cooler coupled to thesubstrate, at least one laser assembly coupled to the substrate, whereinthe thermoelectric cooler is thermally coupled to the at least one laserassembly and thermally isolated from the substrate.

In accordance with another aspect of the present disclosure an opticaltransceiver module is disclosed. The optical transceiver modulecomprising a housing defining a cavity, a substrate at least partiallydisposed in the cavity, a thermoelectric cooler coupled to the substratewithin the cavity, a transmitter optical subassembly (TOSA) arrangementcomprising at least one laser assembly coupled to the substrate withinthe cavity, wherein the thermoelectric cooler is thermally coupled tothe at least one laser assembly and thermally isolated from thesubstrate, and a receiver optical subassembly (ROSA) arrangement coupledto the substrate within the cavity.

In accordance with another aspect of the present disclosure a heaterdevice for use within transmitter optical subassemblies (TOSAs) isdisclosed. The heater device comprising a base, a resistive heatingelement disposed on the base, an electrical conductor disposed at leastpartially on the resistive heating element, the electrical conductor toelectrically connect a laser diode (LD) with associated LD drivingcircuitry, a layer of electrically insulating material disposed betweenthe electrical conductor and the resistive heating element, and whereinthe layer of electrically insulating material thermally couples theresistive heating element to the electrical conductor to communicateheat generated by the resistive heating element to the LD via theelectrical conductor, and wherein the layer of electrically insulatingmaterial electrically isolates the resistive heating element from theelectrical conductor.

In accordance with another aspect of the present disclosure a lasersubmount for use within transmitter optical subassemblies (TOSAs) ortransmitters is disclosed. The laser submount comprising a substrate, alaser diode (LD) coupled to the substrate, a first electricallyconductive path disposed on the substrate to electrically couple the LDto LD driving circuitry, and a heater device disposed on the substrate,the heater device having a resistive heating element and an electricalconductor thermally coupled to each other, the electrical conductorconfigured to provide at least a portion of the first electricallyconductive path to electrically couple the LD with the LD drivingcircuitry and configured to communicate heat from the resistive heatingelement to the LD, wherein the resistive heating element is electricallyisolated from the electrical conductor.

In accordance with another aspect of the present disclosure an opticaltransceiver module is disclosed. The optical transceiver modulecomprising a housing, a transceiver substrate disposed at leastpartially within the housing, at least one transmitter opticalsubassembly (TOSA) assembly coupled to the transceiver substrate, the atleast one TOSA assembly comprising a laser submount, a laser diode (LD)coupled to the laser submount, a first electrically conductive pathdisposed on the laser submount to electrically couple the LD to LDdriving circuitry, a heater device disposed on the laser submount, theheater device providing at least a portion of the first electricallyconductive path and configured to communicate heat to the LD via one ormore wire bonds, and a receiver optical subassembly (ROSA) arrangementcoupled to the transceiver substrate.

While the principles of the disclosure have been described herein, it isto be understood by those skilled in the art that this description ismade only by way of example and not as a limitation as to the scope ofthe disclosure. Other embodiments are contemplated within the scope ofthe present disclosure in addition to the exemplary embodiments shownand described herein. Modifications and substitutions by one of ordinaryskill in the art are considered to be within the scope of the presentdisclosure, which is not to be limited except by the following claims.

What is claimed is:
 1. A heater device for use within transmitteroptical subassemblies (TOSAs), the heater device comprising: a base; aresistive heating element disposed on the base; an electrical conductordisposed at least partially on the resistive heating element, theelectrical conductor to electrically connect a laser diode (LD) withassociated LD driving circuitry; a layer of electrically insulatingmaterial disposed between the electrical conductor and the resistiveheating element; and wherein the layer of electrically insulatingmaterial thermally couples the resistive heating element to theelectrical conductor to communicate heat generated by the resistiveheating element to the LD via the electrical conductor, and wherein thelayer of electrically insulating material electrically isolates theresistive heating element from the electrical conductor.
 2. The heaterdevice of claim 1, wherein the base comprises a material with a thermalconductivity of 1.5 Watts per meter-Kelvin (W/m-K) or less.
 3. Theheater device of claim 1, wherein the base comprises Quartz.
 4. Theheater device of claim 1, wherein the base comprises a cuboid shape. 5.The heater device of claim 1, wherein the base comprises a plurality ofprojections defined by a groove, the plurality of projections to mountthe base to a substrate.
 6. The heater device of claim 1, wherein theresistive heating element comprises a layer of a metal disposed on thebase and first and second electrically conductive terminals formed of asecond metal electrically coupled to the layer of metal, the layer ofmetal being a different metal than the second metal of the first andsecond electrically conductive terminals.
 7. The heater device of claim6, wherein the layer of metal comprises Tantalum nitride (TaN) and thesecond metal of the first and second electrically conductive terminalscomprises Gold (Au).
 8. The heater device of claim 6, wherein the secondmetal of the first and second electrically conductive terminals has anassociated electrical resistivity that is less than the electricalresistivity of the layer of metal.
 9. The heater device of claim 6,wherein the layer of electrically insulating material electricallyisolates the layer of the metal from the electrical conductor.
 10. Theheater device of claim 1, wherein the layer of electrically insulatingmaterial comprises at least one of Silicon dioxide (SiO2), AluminumNitride (AlN), Aluminum Oxide (Al2O3), Silicon Carbide (SiC), SiliconNitride (Si3N4), and/or Polyimide.
 11. The heater device of claim 1,wherein the electrical conductor comprises at least one matchingresistor.
 12. The heater device of claim 1, wherein the resistiveheating element extends substantially transverse relative to theelectrical conductor, and wherein a first end of the electricalconductor is disposed on a first side of the resistive heating elementto provide a first electrical terminal, and a second end of theelectrical conductor is disposed on a second side of the resistiveheating element to provide a second electrical terminal.
 13. The heaterdevice of claim 12, wherein the second electrical terminal provided bythe second end of the electrical conductor has a larger overall surfacearea relative to the overall surface area of the first electricalterminal provided by the first end of the electrical conductor.
 14. Alaser submount for use within transmitter optical subassemblies (TOSAs)or transmitters, the laser submount comprising: a substrate; a laserdiode (LD) coupled to the substrate; a first electrically conductivepath disposed on the substrate to electrically couple the LD to LDdriving circuitry; and a heater device disposed on the substrate, theheater device having a resistive heating element and an electricalconductor thermally coupled to each other, the electrical conductorconfigured to provide at least a portion of the first electricallyconductive path to electrically couple the LD with the LD drivingcircuitry and configured to communicate heat from the resistive heatingelement to the LD, wherein the resistive heating element is electricallyisolated from the electrical conductor.
 15. The laser submount of claim14, further comprising a layer of electrically insulating materialdisposed between the electrical conductor and the resistive heatingelement to electrically isolate the electrical conductor from theresistive heating element.
 16. The laser submount of claim 14, whereinthe LD comprises an electro-absorption modulated laser (EML) having alasing region and a modulator region.
 17. The laser submount of claim16, wherein the lasing region of the EML is electrically coupled to thefirst electrically conductive path via the electrical conductor and anelectrical interconnect having a first end electrically coupled to theelectrical conductor and a second end electrically coupled to the lasingregion of the LD.
 18. The laser submount of claim 17, wherein theresistive heating element communicates heat to the lasing region of theEML via a thermal communication path that extends through a layer ofelectrically insulating material to the electrical interconnect by wayof the electrical conductor.
 19. The laser submount of claim 17, whereinthe electrical interconnect comprises at least one wire bond, the atleast one wire bond to communicate heat to the lasing region of the EMLfrom the resistive heating element.
 20. The laser submount of claim 16,wherein the electrical conductor comprises at least one matchingresistor disposed on the heater device to provide impedance matching fora driving signal to be provided to the modulator region of the EML viathe first electrically conductive path.
 21. The laser submount of claim20, wherein the at least one matching resistor is disposed on theresistive heating element and electrically isolated from the resistiveheating element based on a layer of electrically insulating material.22. The laser submount of claim 20, wherein the modulator region of theEML is electrically coupled to the first electrically conductive pathvia the at least one matching resistor of the electrical conductor andan electrical interconnect having a first end electrically coupled tothe at least one matching resistor and a second end electrically coupledto the modulator region of the EML.
 23. The laser submount of claim 22,wherein the electrical interconnect comprises at least one wire bond,the at least one wire bond to communicate heat to the modulator regionof the EML from the resistive heating element.
 24. The laser submount ofclaim 22, wherein the resistive heating element communicates heat to themodulator region of the EML via a thermal communication path thatextends through a layer of electrically insulating material to theelectrical interconnect by way of the at least one matching resistor.25. An optical transceiver module, the optical transceiver modulecomprising: a housing; a transceiver substrate disposed at leastpartially within the housing; at least one transmitter opticalsubassembly (TOSA) assembly coupled to the transceiver substrate, the atleast one TOSA assembly comprising: a laser submount; a laser diode (LD)coupled to the laser submount; a first electrically conductive pathdisposed on the laser submount to electrically couple the LD to LDdriving circuitry; a heater device disposed on the laser submount, theheater device providing at least a portion of the first electricallyconductive path and configured to communicate heat to the LD via one ormore wire bonds; and a receiver optical subassembly (ROSA) arrangementcoupled to the transceiver substrate.
 26. The optical transceiver moduleof claim 25, wherein the LD comprises an electro-absorption modulatedlaser (EML) having a lasing region and a modulator region.
 27. Theoptical transceiver module of claim 26, wherein the heater devicecomprises: a base with resistive heating element disposed thereon; anelectrical conductor disposed on the resistive heating element, theelectrical conductor providing a portion of the first electricallyconductive path that electrically couples the LD to LD drivingcircuitry; and a layer of electrically insulating material disposedbetween the electrical conductor and the resistive heating element toelectrically isolate the electrical conductor from the resistive heatingelement and thermally couple the resistive heating element to the EMLvia the one or more wire bonds.
 28. The optical transceiver module ofclaim 25, further comprising a thermoelectric cooler coupled to thetransceiver substrate, the thermoelectric cooler being thermally coupledto the at least one TOSA assembly and thermally isolated from thetransceiver substrate, and wherein the thermoelectric cooler defines athermal communication path that extends from the at least one TOSAassembly to the housing without passing through a hermetically-sealedcavity.